EN
By the use of isolated strains of B. nodosus classified as A-F serotypes some trials were undertaken to develop a vaccine against ovine footrot. On the basis of immunoge- nicity three strains of A, C and F serotypes were selected which induced in immunized animals the highest level agglutinins. The strains were used to prepare a condensed vaccine which was applied under field conditions. Under study were two groups of sheep, including 410 animals in the first one and 180 in the second flock inflicted with footrot permanently in the past. In comparison to former years, the vaccine reduced the percentage of infection during the 8 months of observations from 25 to 3.5% in the first flock and from 45 to 3.3% in the second one. The results, though carried out on a limited number of animals, turned out very encouraging. Nevertheless, further examinations are necessary to improve the vaccine by other immunogenic serotypes.